Intermittent Signal Dropouts and Pixelation
bugged
Newbie

I have had FIOS since 2007 and up until a couple of months ago have had flawless service.  I am in the central VA area.  I am now experiencing signal dropouts and picture degradation on any channel in the 327 Mhz - 345 Mhz range.  These problems are intermittent and occur on channels 568, 744, 780, 781.  I have one TV and no splitter with a 12 db attenuator inline with the cable that comes directly from the ONT.  I have a TV cable card for signal decryption with no set top box.

I have tried no attenuation of the signal and different levels of signal attenuation without correcting the problem.  I have also tried eliminating obvious sources of interference, such as wireless routers, computers, and phones.  A tech at the Fiber Solutions Center said that no one else in my area has reported the problem.

Again, the problem is intermittent.  It can occur at random times during the day and night.  I can have up to a week of problem-free service, followed by several hours where the broadcasts on these channels are unwatchable.  All other channels are fine.

I don't have another TV for testing.  Any thoughts or suggestions appreciated.

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Re: Intermittent Signal Dropouts and Pixelation
GaryDoug
Specialist - Level 1

When I had a similar problem on another service, it was a damaged cable with an open shield.The cable was slightly underground and someone had hit it with a shovel while "gardening". The water has gotten in and corroded the shield strands making it open circuit between the ends. I discovered it with an ohmeter by shorting one end with a wire jumper and using the ohmeter function at the other end (should read near 0 ohms, but it read over 10megs).

The symptoms I had were usually late at night and the same as yours.

This could be caused by many reasons, including low or high signal strength. Or even a defective TV. Or a bad fiber cable.

Re: Intermittent Signal Dropouts and Pixelation
bugged
Newbie

Thanks for the reply.  Diagnostics on my TV indicate a low signal strength.  I've noticed the SNR on these channels drop below 32 when the problem occurs.  But then it will magically fix itself at some point and the SNR will revert back to the 37-38 level.  I'm no expert, but I would be very surprised if the TV tuner was defective within a narrow frequency band.  Maybe the ONT has developed a glitch.  I dunno...

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Re: Intermittent Signal Dropouts and Pixelation
GaryDoug
Specialist - Level 1

I have found that the threshold for reliable operation is around 30-33db. Normal for me is 36-37. When I experienced the issues with the broken coax shield it was setting at 30-31db. Did you check your cable(s) for intermittant opens at the connectors?

Also, the next time this happens, check the S/N at some other frequency , for example: Ch 665, (507mhz). See if it's low also. The ones at 327-345 may be just the weakest ones. If the others are low too, it's more of a general problem.

One other long-shot possibliity might be if you are near an airport, especially a  military installation. They use the 328-335 MHZ band for radionavigation. Of course, that shouldn't affect the cable signals unless there is a loss of shielding on the cables.

good luck

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Re: Intermittent Signal Dropouts and Pixelation
spacedebris
Master - Level 2

I know it sounds silly, but try disconnecting the coax from the STB and the ONT and then reconnect them. I had a similar problem, only mine was a little more frequent, that turned out to be simply a poor connection. Re-seating the coax fixed it.

You may also want to replace the connectors on the coax. It may be that they are not shielding the connections properly. This is a cheap and easy thing to do. It may not help but it cant hurt to try.

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Re: Intermittent Signal Dropouts and Pixelation
bugged
Newbie

I have tried disconnecting and reconnecting the coax at the TV end but not at the ONT.  The ONT connection appeared to be solid so I left it alone.  But I'll give it a shot anyway.  Thanks for the suggestion.

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Re: Intermittent Signal Dropouts and Pixelation
GaryDoug
Specialist - Level 1

How long is the coax cable from the ONT to the TV? Can you examine the entire length of the cable or is it hidden anywhere?

If you can see the entire cable and are sure there is no physical damage that is visible: I would try slowly moving the cable near each connector end while someone watches the SNR display on the TV. If it intermittantly drops, you have found the problem. If not, you can probably eliminate the cable as cause. Note that the TV SNR display may not update quickly, so move the cable slowly. A Motorola or S/A  DVR, for example, updates only every 5 seconds.

If you are technically able, and interested, read on...

If a shield connection is lost entirely, it would probably drop the SNR to about 25. A partial or high-resistance connection would be somewhat higher, in the 25-36 range. You can see this yourself with a simple demonstration. Disconnect the cable at the TV. Use a short coax jumper, like the one probably used for the attenuator, connected to the TV. Now, jumper the free end of the short coax cable center conductor to the free end of the center conductor of the long cable you disconnected from the TV. You can use an alligator or "minihook" jumper, or just hold the two center conductor tips together (keeping the connector bodies separate) while someone reads the SNR at the TV. This simulates loss of the shield conductors. If you use the jumper method, you can also jumper the connector bodies together and notice the SNR value again. This would simulate the loss of shield for a length or wire equal to the combined lengths of the 2 jumpers. When I performed this on my setup, and used two 12" jumpers, I got an SNR of 30db. You see where I'm going with this? An intermittant loss of 2 feet of shielding can possibly give you the results you are seeing. Just one of many possibilities.

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Re: Intermittent Signal Dropouts and Pixelation
lasagna
Community Leader
Community Leader

Another good spot to check is splitters ... I had a similar situation which made absolutely no sense to me where my TV's in the upstairs bedrooms on the other side of a long run of older coax were having no problems but the TV in the living room connected on all new coax and only a short distance from the ONT was having dropouts on certain channels.   At first I thought it was a faulty STB, but the problem stayed with the location and didn't follow the box when I swapped locations (something worth trying if you have more than one STB).  I finally replaced a splitter -- one provided by Verizon -- with one I had purchased some time ago from a local big box store and the problem went away.

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Re: Intermittent Signal Dropouts and Pixelation
bugged
Newbie

Yes, I should be able to examine the entire length of the coax.  I would estimate it to be about 15 to 20 feet at the most. I assume I am looking for some visible break in the outer layer of the cable? 

Thanks for the suggestion.

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Re: Intermittent Signal Dropouts and Pixelation
bugged
Newbie

Thanks.  I have no splitter in my setup, but actually tried adding one to see if that would make a difference!

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